Process and an apparatus for the production of crimped filaments



H. PROCESS AND AN APPARATUS FOR THE PRODUCTION OF CRIMPED FILAMENTS May 6,1969 BACH 3, 8

Filed Sept. 20. 1966 I INVENTOR.

HANS BA CH.

United States Patent 3,441,988 PROCESS AND AN APPARATUS FOR THE PRODUCTION OF 'CRIMPED FILAMENTS Hans Bach, Dormagen, Germany, assignor to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany Filed Sept. 20, 1966, Ser. No. 580,682 Claims priority, applicatigg Gtgrmany, Sept. 29, 1965, F 30 Int. c1. D02g 3/00 U.S. Cl. 28--1 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for the production of synthetic thermoplastic filaments having a fixed crimp, by introducing the filament or bundle of filaments into a heated gap, and to an apparatus for carrying out the process.

It is known that filaments from synthetic thermoplastic high polymers can be crimped by heating and guiding them around an edge. In addition, filaments of this kind can be crimped by introducing them into a compression chamber at an elevated temperature. It has also been proposed to crimp filaments by introducing them between rollers Whose surfaces are inclined towards one another, so that the filaments are guided through the gap thus formed.

In the so-called false-twist process, the filaments are twisted, thermally fixed and then re-twisted. Firstly, these known processes involve the use of expensive apparatus and, secondly, the crimp effect obtained does not come up to expectations. In particular, the stability (fixing) of the crimp leaves much to be desired.

We have now found a process and an apparatus for the production of synthetic thermoplastic filaments with a particularly well fixed crimp in which the filaments are guided into a wedge-gap zone (V-gap zone) where they are heated, whilst the drawing off of the filaments is retarded or slowed down and the speed at which the crimped filaments emerges from'the Wedge-gap (V-gap) zone is also reduced.

The V-gap zone is formed by a heated roller and a Wedge-gap (V-gap) segment at the end of which there is a filament brake. The filaments are introduced into the V-gap zone either directly from the cop or bobbin or by way of a feed mechanism in the form of a stretching device, for example. The process is carried out at temperatures in the range of from 80 C. to 180 C. Among the many synthetic thermoplastic filaments, those of polyamides (polycaprolactam and polyhexamethylene adipic amide) are particularly suitable for the process.

The gap between the segment and the roller and the bearing pressure are adjusted in such a way that the filaments are carried at the full peripheral speed of the roller. The filament brake creates the necessary counter pressure on the issuing filaments, so that a crimp wave is built up in the V-gap.

The bundle of filaments is then carried further by the rotating roller and is pressed against the inner surface of the fixed segment. This results in a slight profile deformation whereby the filaments are sharply bfint (crimped). Since this takes place at the moment 01 maximum bearing pressure on the heated roller, the crimp is adequately fixed.

An apparatus for carrying out the process is shown in FIG. 1 in the form of a crimping attachment.

A filament 1 travels around a delivery mechanism 2 into a gap formed by a fixed or stationary crimping segment 4 and a heated crimping roller 3. The peripheral speed of the crimping roller 3 is higher than that of the delivery roller 2 so that the filament is taken between the crimping roller 3 and the crimping segment and is forced out via the brake flap 7.

In order to obtain an optimum crimp effect for different filament materials and thicknesses, the following possibilities of adjustment are provided:

(a) The crimping roller 3 is adapted to be heated either by steam or by electricity, the temperature being variable within wide limits.

(b) The ratio between the peripheral speeds of the roller 2 and the crimping roller 3 is adjustable.

(c) The crimping segment 4 is adjustably suspended from the support 5, and is mounted in the support 6 in such a way that it can be adjusted under spring tension.

(d) The brake flap 7 is rotatably mounted in the crimping segment 4, whilst its bearing pressure on the crimping roller 3 can be varied by weight or by spring pressure.

FIG. II shows the wedge-gap (V-gap) arrangement With the brake flap 7 replaced by an adjustable stripping edge or doctor 15. In this case, too, an optimum crimping eflect can be obtained by selecting the clearance angle and the distance between the yarn outlet and the doctor .15.

In the following examples, the crimping effect is characterised by measuring the degree of shrinkage or contraction after steam treatment. A shrinkage of 30% means that the crimped filament undergoes a decrease in length of 30% during steam treatment.

EXAMPLE 1 A stretched filament bundle of nylon 6 (polycaprolactam) with an overall denier of 1,200 and an individual denier of 20, is treated in an apparatus of the kind shown in FIG. I under the following conditions.

The gap at 5 is set at 0.3 mm. The peripheral speed of the roller 3 is m./min. The temperature of the roller 3 is kept at C.

Under these conditions, a crimped filament is obtained which undergoes 25% shrinkage on treatment with steam.

EXAMPLE 2 A stretched filament bundle of nylon 6 (polycaprolactam) with an overall denier of 1,200 and an individual denier of 20, is treated in the apparatus shown in FIG. I. The gap at 5 is set at 0.2 mm., the temperature of the roller is kept at C. and the peripheral speed of the roller 3 is set at 300 m./min.

The shrinkage of a filament treated in this Way was measured as 33.5%.

EXAMPLE 3 A stretched filament bundle of nylon 66 (polyhexamethylene diimine adipate) with an overall denier of 1,300 and an individual denier of 18 is treated in an apparatus of the kind shown in FIG. I under the following conditions.

Gap at 5:02 mm. Temperature of the roller 3: C. Peripheral speed of the roller 3:200 m./min.

After steam-treatment, shrinkage of the sliver amounts to 39.5%.

What I claim is:

1. A process for the production of synthetic thermorlastic filaments having a fixed crimp which comprises ntroducing the filaments into a wedge-gap zone formed )y the outer surface of a supporting and crimping roll For said filaments and the inner surface of an adjustable :egment at least partially surrounding the outer surface at said roll, heating said filaments in said zone at a temaerature between 80 and 180 C. while passing said ilaments, on said roll in contact with said segment, and retarding said filament movement whereby the resultant, :rimped filaments are Withdrawn from said retarding step at a lower rate than said filaments leave the wedge-gap zone.

2. The process of claim 1 wherein the filaments are of polycaprolactam.

3. An apparatus for the production of synthetic thermoplastic filaments having a fixed crimp comprising a crimp roller whose external surface is at least partially surrounded by an adjustable, supported, gap-forming segment and means for retarding the exit of crimped filaments to a speed less than the speed at which such filaments are carried by said crimp roller from the gap zone formed by said crimp roller and said segment.

4. The apparatus of claim 3 wherein said gap zone is uniformly heated.

5. The apparatus of claim 3 wherein the retarding means is rotatably mounted on the support of said gapforrning segment.

References Cited UNITED STATES PATENTS 2,263,712 11/ 1941 Wrigley et a1. 3,146,512 9/1964 Heijnis. 3,174,206 3/ 1965 Mattingley et al. 3,177,556 4/1965 Van Blerk.

FOREIGN PATENTS 1,125,524 7/1956 France.

LOUIS K. RIMRODT, Primary Examiner.

US. Cl. X.R. 28-72 

